Method of producing a gaseous motive fluid with pulverized fuel



Nov. 4, 1952 w. ROBINSON ET AL METHOD OF PRODUCING A GASEOUS MOTIVE FLUID WITH PULVERIZED FUEL Filed Feb. 9, 1946 5 l STARTING COMPRESSOR TURBINE MOTOR ASH SEPARATOR COOLING AIR ADDITIONAL COMBUSTION Al PULVERIZED COAL AND COMBUSTION AIR ASH SEPARATOR I ATTO NEY Patented Nov. 4, 1952 Memos oryj PR'ODUCING A; GASEOUSI" MOTIVE- FLUID wrrn PULVERIZED FUEL w t r aobi s a flili bus, Ohio, assignors;

Allis-Chalmers/.Manufacturing Company,

ertrand A Landry, Columby mesne assignments, to

Mil

Wa'ukee," Wisi, acorporation .of Delaware Application February 9, 1946, Serial No; 646,542 71 claims. (Cl. so-i-saoz) This invention relates? generally to the comebustion of: pulverized: fuel-r containing: noncom bustiblesolid material; andis directed toward and contemplates; the ;-production of large quantities-of a 'he'ated-high'velocity motive fluid which: is. suitablefor operating; gas; turbines,- and the likeand which consists,qatleastdn part;. of rprod nets of; combustion resulting? from: burning-such fuel in suspension; in;v angaseousrcombustion sup portingmedi'um-or-carrier: I I

In 1 this iconnect-ion-ga:heretofore'commoncon ception is that I ifpulverized: solid fue'l such as: coal,;=isburned? in suspension; under; conditions: producing ash particles of small size, the erosiveness- .of 2 the 1 suspended ashparticles; Will be' so minimized gasvto render practical; the'gformatlon and; use of. motive fluids asherei-na-bove'indicate ed. And this conception hasbeentconfirmedrby, extensive experimentationi dm that ithas beenfound that the" erosiveieflect of suspended: ashparticles in general decreases: as; thev size: of the: particles decrease and, that qthedecrease-in erosive' effectvis-.quite rapid-as the "size of ;the.- particles becomes-less than: 20- microns; 7

However, it has also beenfound.that'even if: solid fuelfis burned in suspension-underrconditionse producing; extremely-1; small a ash-particles; the ash. content ofz-the resulting stream of moti-vez fluid. is; relatively. high and the erosive efiect of-v the a'sh particles suspended: therein issufficiently; great; to render; the; life; expectancy of turbine.- parts, particularly the 'blading,- entirelwtoo shortfor; satisfactory commercial-Z application=- And although'thequantity of. suspendedaashvparticlesa can; be r reducedtth roughtheguse oii. suitable *fiyg.

ash separators, itisl. extremely rdinicult iandw ene erally impracticable to thus reducevthe quantity; of small suspended .ash;.particlessufiioientl y to.- increase: the life-:expectancyeoi turbi-nerpartsetoi afsatisfactory;practicalextentsv Anotherrheretofore common and somewhat {re-- lated I conception is thatyif pulverizedesolidrzfuel; is' burned in suspension atla a; 10W: temperature; the. resulting; ash particles. willibe sufifioiently soft to rendei' the erosivenesaor lsach par-ticleslneg-li. iiblef Htwever; extensive.experiihntation. negatives the 'corrjectness if of. misconception .in'I that. even: the small a's'h particles 1 resulting. frfom. I. the low. temperature "combustiofi'of pulverized solid; lfuel. in: suspension, are. in .fact. quite.- hardifland.haver a ""d .configuiia'tion which ,materially increases: sivefaction nbbjects contacted thereby: 1611;. the. jaggecl'l configuration -oi the.

I I partwles renders, a1 mechanical separation of same from the carrier gas stream. particularly difiicult as such particles-present a relatively large surface area-and consequently attai'nfa} velocity more nearly equal to that, of the carrier fluid than do smooth ash particles of similar Weight.

And therefore the present invention is par.- ticularly concerned with and has.v as an object the production of a heated, high velocity motive fluidofthe character. mentioned hereinabove by burning pulverized fuel. containing" noncom-' b ustible solid" materialfina manner su'ch'that the noncombustible solid particles inherently present :in suspension in the resulting stream of.

combustion products .are of a configuration conducive ;.to-minimizing the erosiveeffe'ct of such particles and/orflofia character besttoenable' a large" portion of the particles to be readily' re'- moved from" the. carrier stream bypassing the stream through, a". conventional mechanical separator of simplified construction? v v Anotherobject; o' ffthe presentinvention is 'toproducea heated, high velocity motive fluid, con

sisting atleast'in'part of products oi combustiom by" burningjpulverized ruer containing madam: bu'stib-le-f solid" matter in amanner eiiective' to minimize the formation of lightweight-and/o'r jagged ash particles? Anothe'r'" object f the" present inventioniis to produce a heated; high" velocitir motive fluid;

consisting at least-in part ofproducts 'o'f co'm blistifiiby bllTIliil g pulverized fuel containing 1 noncombustible solid material in a mannerQsu'ch that the noncombustible solid material inher e'ntly 'present in suspension in the resulting stream 01 combustion' products is the for-info? particles preponderately of generally spheroidal" shape;

combustion, vby burningcpulverized fuel :contain ing noncombustible solid materialin -a manner. such that the noncombustible solid. material is ,-.present. in suspension in the. resulting V sitreamgioi" combustion. products: in the form of .pai't i t-lesv preponderatlyof large size and"general'l yaspheroidal shape. I

In. accordance this invention, one; or. more 'of the; hereinabove :sta'ted objects g-may be readilyaccomplished through the [provisions-and operation of apparatus f oriburning pulverized solid. fuel in suspension; in a combustion-supporting'gaseous carrier unde rlrconditions.p godqcin high temperature.-zone.through which? the: non- 3 combustible solid particles pass in confined suspension and become sufficiently fluid in passing therethrough to assume a generally spheroidal shape, and wherein movement of the fluid particles is preferably such as to cause such partitales to collide and agglomerate and thereby form larger and heavier spheroidal particles before solidification occurs.

The manner of practicing the methods of the present invention will become readily apparent as the disclosure progresses and particularly points out, as hereinafter fully set forth, the various features, steps and advantages considered of special importance with respect to such methods. And in this connection, attention is directed to the following detailed description and appended claims, reference being had to the accompanying drawing illustrating one form of apparatus suitable for practicing the invention and in which:

Fig. 1 is a schematic showing of a simple continuous combustion gas turbine system embodying apparatus operable in accordance with this invention; and

Fig. 2 is an enlarged view of a modified flame and noncombustible particle confining structure illustrating the suspension and formation of particles of'preferred shape and/or size. I

Referring to the drawing, it will be seen tha apparatus for use in connection with the practice of the present invention may include inner and outer concentrically arranged annular shells land 2 forming therebetween an annular space I 3 surrounding the combustion zone 4 definedby inner shell i and a pair, of conduits 6 and 1 connecting zone 4 with suitable conventionally controllable sources of pulverized fuel and air not shown). If desired, the interior of shell I may be provided with a suitable refractory lining B and with a converging discharge end portion 9, as shown in Fig. 2. The discharge, end por tions of conduits 6 and I may be arranged in concentric coaxial relation with respect toeach other and with respect to the longitudinal axis of shelli. And with such an arrangement ofconduits, it is generallypreferable to introduce the mixture of primary air and fuel (in this case pulverized coal suspended in an air stream) into zone 4 throughconduit 6 and to introduce whatever additional air may be required in such zone order to further control combustion and temperature conditions therein through conduit 1. V g

Cooling air may be controllably supplied to annular space 3 by means ofa compressor I l and a valve controlled conduit [2 connecting the discharge of compressor II with the interior of shell 2 ate. point adjacent the closed or burner end thereof. Outer shell 2 extends a considerable distance longitudinally beyond the discharge end-of shell I and provides a cooling zone 13' wherein the air issuing from annular space 3 mixes with and cools the combustion products issuing from zone 4 at a point adjacent the discharge end of shell I. The discharge end of outer shell 2 is suitably connected with a con ventional separator M which is in turn suit' ably connected, as by means of a conduit IS, with the inlet portion of a turbine |'I drivingly connected with the compressor. And a suitable starting motor l8 may beselectivelydrivingly connected with the compressor II and turbine I! through a clutch or the like i 9.

A gas turbine system of the type hereinab briefly described may be readily started and 015- erated as heretofore known and when thus operated the coaction and functioning of the various elements of such a system are in general as follows: cooling air is delivered to annular space 3, a mixture of fuel and air is' burned in zone 4 and perhaps to soine extent in zone 92, air from space 3 and combustion products from zone 4 combine and mix in zone [3 to form a resulting motive fluid having a safe Working temperature and the resulting motive fluid passes through separator (4, wherein the heavier ash particles are removed from the fluid and then into turbine [7.

However, as hereinbefore pointed out the life expectancy of a turbine driven by motive fluid produced by the heretofore known methods of operating such systems with a fuel containing noncombustible solid materia1 is entirely too short for satisfactory commercial application. And in this connection it has been found that the ash content of the motive'fluid thus produced is relatively high and that the ash particles present in such fluid are preponderately of lightweight and jagged configuration which is probably due to the fact that even if an ash fusing temperature is maintained in the combustion zone proper, the rate of travel of the combustion gases and therefore of the ash particles passing therethrough is so rapid that most of the ash particles do not become sufficiently fluid in passing throughthe combustion zone to attain a generally spheroidal shape before entering the ,cooling zone.

In accordance with applicants method, the pul-jv verized coal and air mixture introduced through.

conduit 6 and whatever-additional air is introduced through conduit 1 are quantitatively adjusted so that despite the loss of heat to the air or other gas in the surrounding annular space 3, the prevailing temperature in zone 4, particularly ad jacent the discharge end thereof, is sufficiently high to fuse ash particles passin therethrough, and so that the turbulence and/or axial velocity of the combustion gases passing through zone 4 is sufficient to suspend and carry ash particles th'erethrough at particles become fluid and attain a generally spheroidal shape (see Fig. 2) before entering the cooling zone. And in this connection, it should be noted that when the shell or other structure de-' fining zone 4 is shaped to form a converging discharge portion, as illustrated in Fig. 2, the" velocity and turbulence of the combustion gases and of the ash particles suspended therein will increase considerably in a manner materially iricreasmg collisional agglomerations of the fluid particles passing through the discharge portion of the combustion zone. In addition to quantita tively adjusting the primary air and fuel mixture In practicing the presentinvention, it

be borne in mind that the prevailing temperature n zone 4 may be'varied considerably depending upon the fusion temperature of 'thenoncombustible solid particles or' ash present in the" a rate such that most or the -resulting ='stream of combustion gas.v However, although the chemical composition of different particles of coal ash varies widely and consequently :the fusion "temperatures of such particles "also .vary widely, most coals have an ash fusion temperature of 2800 F., or less, and if the-fuel and air delivered to zone 4 is quantitatively; adjusted to .produce therein. aprevailin "temperature of-2800 F., the ash of most coals will become sufficiently fluid to attain a spheroidal shape before leaving such zone, providing their rate of travel therethrough is not too, rapid. The ash fusion temperatures. of the commonly used coals can usually be obtained from the supplier,

although if desired or considered necessary, the I ash fusion characteristics of any coal can be readily; determined by the standard-American 'Societyfor Testing Materials method. And once theashfusion temperature of; the coal; to. be usedis ascertained, all that has to be donein order to. produce generally spheroidal ashlparti- 'cles isto quantitatively adjust the fuel and air delivered to zone 4 as hereinbefore indicated, bearingin mind of course, that the proportion ef-primary air and pulverized fuel used depends on the ignition characteristics of; the; coal and that-the introduction of additional air into zone 4 primarily for the purpose of completing-combustion; and regulatingthe; temperature.- prevail,- in the ein.

Motive fluid produced in accordance with this invention is far superiorfor the operatio-nzof turbines 'and'the likethan is motive fluid producedby the heretofore known methods of operation in that, as previously pointed out,

sshcm da ash a t l s a l s erosive efiect on; parts contacted thereby and can bemore readilyremoved from a carrier gasstream than can jagged ash particles of similar weight produced by such known methods. And although the ash content'of a motive fluid produced so as to contain ash particles preponderately of generally spheroidal form does, even if the ash particles are small and of light. weight, materially prolong the life expectancy of turbines and the like operated thereby, the ashcontentof'a motive fluid containing spheroidal ash particles can be further materially'reduced by mechanical separationif the mass of the ash particles is increased by forming same under conditions producing 'collisional,agglomerations thereof.

' ,The, present inventionmay be practiced with the aid of apparatus differing] materially froih thatherein'disclosed for'purposes of illustration md'thej'nature'and character of the pulverized jfuel and of the combustion supporting and. cooling gasj'or gases employed may also differand "vary materially provided a heated, high velocity motive fluid, consisting at least in part of prodnets of combustion, is produced by burning pulverized fuel containing noncombustible solid material under conditions such that the noncombustible solid material is present in suspension in the resulting stream of combustion products in the form of particles having a configuration minimizing the erosive effect of such particles on objects contacted thereby and/or of a character best to enable a large portion of the particles to be readily removed from the carrier stream by passing the stream through a separator of conventional construction. And it should therefore be understood that it is not intended to limit the present invention to the use of the particular apparatus, fuel and gases herein pointed out as being satisfactory for practicing same as various modifications. may occur to persons :skilleclin; the

art.

It is claimed and desired to secure by Letters Patent:

1. A .method of producing large quantities-of heated high velocity motive fluid including prod.- -ucts. of combustion formed by burning in a-rconflned burning zone pulverized fuel containing noncombustible solid material, in suspension ;in .a combustion supportingcarriergas, said method comprising the transforming of said included noncombustible solid material into a particle form having a minimum erosive effect, by the stepslof quantitatively regulating the fueland gas introduced into said burningzone to'create .a temperature in said zone sufficientlyhigh to cause the particles to fuse; then confining and .directingisaid gas andfusedparticles, in a cylindrical streamito create a gas-flow-conditioneffectiveto maintainsaid particles in suspension-long enough to insure that :most of said particles,.;at.-

tain a generally. spheroidal shape; and thenat least downstream of said burning zone, ,surrounding said cylindrical stream witha; stream of relatively cool gas to solidify said, fused generally spheroidal particles.

2. A method of producing largequantitiesyof heated high velocity motivefluidincluding;:products-of combustion formed by burning, in anonfined burning zone pulverized fuel containing noncombustiblesolid material in suspensiongina combustion .supporting carrier gas, said, method comprising the transforming of said, included noncombustible solid material into a particle form having-a minimum; erosive effect and ag glomerations. of most of said particles that-rare of sufficient. size to be easily removed: from :said

motive fluid, by the stepsof: quantitatively; regulating: the fuel and gas introduced intosaid buming zone to createa temperature in said'zone sutflciently. high-toscause the; particles to fuse; then confining and directing said gas and'fusedpa-rticlesi in. a cylindrical stream to-createa gas [flow .conditioneffective t maintain said particlesin suspension long enough to insure that most'cf saidvpa-rticles; attaina generally spheroidal shape and collide; to form agglomerations; andthenat least downstream of said burning zone surrounding said cylindrical stream with; a stream of relatively cool gas to solidify said fused generally spheroidal particles and asglo-merations.

3.;Af method of producing large quantities-of heated high velocity motivefluid including products of combustion formed by burning in a conflnedburn-ing zone pulverized fuel containingnoncombustible solid material in suspension :in a combustion supporting carrier gas, said-method comprising the transforming of said included non-combustible solid material into a particle form having a minimum erosive effect and agglomerations of most of said particles that are of sufficient size so as to be easily removed from said motive fluid, by the steps of quantitatively regulating the fuel and gas introduced into said burning zone to create a temperature in said zone sufficiently high to cause the particles to fuse; then confining and directing said gas and fused particles in a cylindrical stream to create a gas flow condition effective to maintain said particles in suspension long enough to insure that most of said particles attain a generally spheroidal shape and collide to form agglomerations; and then at least downstream of said burning zone, surrounding said cylindrical stream with a stream of relatively cool gas directed in the same direction as scram said cylindrical stream, to solidify said fused generally spheroidal particles and agglomerations.

4. A method of producing large quantities of heated high velocity motive fluid including products of combustion formed by burning in a confined burning zone pulverized fuel containing non combustible solid material in suspension in a combustion supporting carrier gas, said method comprising the transforming of said included noncombustible solid material into a particle form having a minimum erosive effect, by the steps of quantitatively regulatin the fuel and gas introduced into said burning zone to create a temperature in said zone sufficiently high to cause the particles to fuse; then confining and directing said gas and fused particles in a cylindrical stream to create a gas flow condition effective to maintain said particles in suspension long enough to insure that most of said particles attain a generally spheroidal shape; and then at least downstream of said burning zone, surrounding said cylindrical stream with a stream of relatively cool gas directed in the same direction as said cylindrical-stream, to solidify said fused-generally spheroidal particles.

5. A method of producing large quantities of heated high velocity motive fluid including products of combustion formed by burning in a confined burning zone pulverized fuel containing noncombustible solid material in suspension in a combustion supporting carrier gas, said method comprising the transforming of said included noncombustible solid material into a particle form having a minimum erosive effect, by the steps of quantitatively regulating the fuel and gas introduced into said burning zone to createa tem- 'perature in said zone sufficiently high to cause the particles to fuse; then confining and directing said gas and fused particles in a cylindrical stream to create a gas flow condition effective to maintain said particles in suspension long enough to insure that most of said particles attain a generally spheroidal shape; and then at least downstream of said burning zone, surrounding said cylindrical stream with a stream of relatively cool gas to mix with said cylindrical stream and solidifysaid fused generally spheroidal particles.

6. A method of producing large quantities of heated high velocity motive fluid including products of combustion formed by burning in a confined burning zone pulverized fuel containing noncombustible solid material in suspension in a combustion supporting carrier gas, said method comprising the transforming of said included noncombustible solid material into a particle form having a minimum erosive effect, by the steps of quantitatively regulating the fuel and gas intro- 8 .duced into. said burning-zone to .createaj temperature in said zone sufficiently high to cause the particles. to fuse; thenconfining and directing said gas and fused particles in a cylindrical stream to create a gas flow condition effective to main.- tain said particles in suspension long; enough to insure that most of said particles attain .a generally spheroidal shape; and then at least downstream of said burning zone, surrounding saidlcylindrical stream with a stream of relatively cool gas directed in the samev direction as said cylindrical stream to mix therewith and solidify said fused generally spheroidal particles.

7. A method of producing large quantities of heated high velocity motive fluid includin products ofcombustion formed by burning in a confined burning zone pulverized fuel containing noncombustible solid material in suspension in a combustion supporting carrier gas, the method comprising the transformingof said included noncombustible solid material into a particle form having a minimum erosive effect and agglomerations of most of said particles that are of sumcient size so as to be easily removed from said motive fluid, by thesteps of quantitatively regulating the fuel and gas introduced into said burning zone to create a temperature in said zone sufficiently high to cause the particles to fuse; then confining and directing said gas and fused particles in a cylindrical stream to create a gas flow condition effective to maintain said particles in suspension long enough to insure that most of said particles attain a generally spheroidal shape and collide to form agglomerations; and then at least downstream of'said burning zone, surrounding said cylindrical stream with a stream of relatively cool gas to mix with said cylindrical stream and solidify said fused generally spheroidal particles and agglomerations.

. WALTER ROBINSON.

BERTRAND A. LANDRY.

REFERENCES CITED The following references are of record in the file of this patent: V I

UNITED STATES PATENTS Number 2,399,884 Noack -May 7, 1946 

1. A METHOD OF PRODUCING LARGE QUANTITIES OF HEATED HIGH VELOCITY MOTIVE FLUID INCLUDING PRODUCTS OF COMBUSTION FORMED BY BURNING IN A CONFINED BURNING ZONE PULVERIZED FUEL CONTAINING NONCOMBUSTIBLE SOLID MATERIAL IN SUSPENSION IN A COMBUSTION SUPPORTING CARRIER GAS, SAID METHOD COMPRISING THE TRANSFORMING OF SAID INCLUDED NONCOMBUSTIBLE SOLID MATERIAL INTO A PARTICLE FORM HAVING A MINIMUM EROSIVE EFFECT, BY THE STEPS OF QUANTITATIVELY REGULATING THE FUEL AND GAS INTRODUCED INTO SAID BURNING ZONE TO CREATE A TEMPERATURE IN SAID ZONESUFFICIENTLY HIGH TO CAUSE THE PARTICLES TO FUSE; THEN CONFINING AND DIRECTING SAID GAS AND FUSED PARTICLES IN A CYLINDRICAL STREAM TO CREATE A GAS FLOW CONDITION EFFECTIVE TO MAINTAIN SAID PARTICLES IN SUSPENSION LONG ENOUGH TO INSURE THAT MOST OF SAID PARTICLES ATTAIN A GENERALLY SPHEROIDAL SHAPE; AND THEN AT LEAST DOWNSTREAM OF SAID BURNING ZONE, SURROUNDING SAID CYLINDRICAL STREAM WITH A STREAM OF RELATIVELY COOL GAS TO SOLIDIFY SAID FUSED GENERALLY SPHEROIDAL PARTICLES. 